This invention relates to cementing oil and gas wells, more particularly, to the manufacturing of a new synthetic glass family in the quaternary phase field of CaO—SiO2-Al2O3-MgO (CSAM). The new synthetic glass family can be used for conventional cementing oil and gas wells operations, for instance to replace the blast furnace slag in mud-to-cement (MTC) technology and also for the construction areas.
Blast furnace slag (BFS) is a by-product produced in the manufacturing of iron, iron ore, iron scrap and limestone fluxes or dolomite fluxes. BFS is nonmetallic and consists primarily of silicates, aluminosilicates and calcium-alumina-silicates. Since slag is a by-product of the manufacturing of iron, the exact chemical composition of the slag is difficult to measure. Differing forms of BFS may be produced by the method used to cool the BFS. BFS may be cooled by rapid water quenching to obtain a granulated slag with cementitious properties.
Due to its cementitious properties BFS has been mixed with Portland cement and water based drilling fluid to create cement slurries that exhibit superior strength and increased thermal and chemical stability over conventional oil well cements. BFS is a commercial by-product that is generally available from slag processors located near iron manufacturing centers. BFS must therefore be imported to regions of the world that do not have blast furnace technology or do not produce iron.
When BFS or Portland cement is mixed with water based drilling fluids a unique cementing technique known as mud-to-cement (MTC) is created. A water based drilling fluid is mixed with the BFS, and/or Portland cement and activators. The mixture is then transformed into cementitious system.
In steam injection techniques and other oil extraction processes that require increased well temperatures, the cementing material used must be able to withstand elevated temperature and thermal cycling associated with steam flood. The conventional Portland cement and also the water based drilling fluids mixed with Portland cement exhibit high thermal degradations. This degradation damages the well resulting in repairs which increase operation costs. In steam injection techniques, the mixture of water based drilling fluids and BFS for MTC technology exhibits a higher compatibility and lower thermal degradation than Portland cement. As a result, BFS is preferred over Portland cement for MTC.
In some regions of the world where steam injection techniques are employed, BFS is not readily available and is therefore imported. The high costs associated with importing BFS compounded by the unknown heterogeneous chemical composition of the BFS, unknown remaining crystalline phases in the BFS and the potential need for an additional milling process is a disadvantage suffered by regions of the world that do not produce BFS.
As a result, there is a need for an economical BFS replacement in regions of the world that do not produce BFS. The new synthetic cementing glass of the present invention may replace BFS in any well cementing operation. The synthetic glass of the present invention is an advantageous well cementing constituent that may be successfully implemented in differing temperature dependent processes, such as the steam injection technique employed for heavy crude oil extraction.